Explanation

(a) $\frac{1}{\lambda} = R\left\lbrack \frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}} \right\rbrack \Rightarrow \frac{\lambda_{\min}}{\lambda_{\max}} = \frac{\left\lbrack \frac{1}{2^{2}} - \frac{1}{3^{2}} \right\rbrack}{\left\lbrack \frac{1}{2^{2}} - \frac{1}{\infty} \right\rbrack} = \frac{5}{9}$